1. Field of the Invention
This invention relates to transmission of information, and in particular to the use of cryptographic encipherment to provide secure communication.
2. Description Relative to the Prior Art
The Vernam cipher is the only known unbreakable method of encryption. Gilbert Vernam developed it in 1917 during WWI while working for AT&T. It makes use of a one-time pad that must be exchanged between the sender and receiver via a secure channel (e.g. face-to-face). The pad must be generated in a totally random manner and must never be reused. Each pad-page must be as long as the largest message. The sender encrypts a plaintext message by combining it with the current pad page via the XOR function. The receiver decrypts the cipher text message by combining it with his current pad page via the XOR function. Both parties discard the current pad page. This procedure repeats itself until the pad is gone. Then, a new pad must be generated and manually distributed in a secure manner. Since each byte in the pad-page sequence is totally random, an attacker is forced to try every possible combination of byte values to arrive at a very large number of potential plaintext meanings.
A method for generating, automatically distributing and using a sufficiently random one-time pad for a Vernam like cipher is disclosed by the present invention.